Wiggins D'Anconia <[EMAIL PROTECTED]> wrote:
> MMKHAJAH wrote:
>> I wonder wether 'use module' compiles only once. I mean that
>> all sebsequent calls don't involve compiling.
>>
> My *guess* is no because that would be silly.
>
> My *semi-proof* is if you have use warnings on and your program compiled
> a module over again that has already been included then it would
> complain about redefining each of the sub routines in that module.
>
> My *guess* is that perl internally either keeps track of the list of
> packages already compiled in, or uses a check on the namespace in some
> manner, though I am slow to think about whether this last bit is
> possible right now. Back to football I guess :-)....................
>
Actually it keeps track of filenames.
(They're in %INC if you want to check.)
And perlfunc confirms that the file won't be
loaded twice:
$ perldoc -f use
...
Imports some semantics into the current package
from the named module, generally by aliasing
certain subroutine or variable names into your
package. It is exactly equivalent to
BEGIN { require Module; import Module LIST; }
except that Module must be a bareword.
...
The "BEGIN" forces the "require" and "import" to
happen at compile time. The "require" makes sure
the module is loaded into memory if it hasn't been
yet.
...
$ perldoc -f require
...
Otherwise, demands that a library file be included
if it hasn't already been included.
...
Note that the file will not be included twice
under the same specified name.
--
Steve
perldoc -qa.j | perl -lpe '($_)=m("(.*)")'
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